Suppression of dynamic stall by steady and pulsed upper-surface blowing

Control of Rotorcraft Retreating Blade Stall Using Air-Jet Vortex Generators

“…Weaver et al 7 suggested that the prime cause of the hysteresis is the extent of the separation present throughout the down-stroke portion of the oscillation cycle. This suggests that blowing from the front AJVG array is effective in accelerating the process of boundary-layer re-establishment during the downstroke.…”

“…Cheeseman and Seed 9 , however, suggested that boundary-layer blowing provided the most attractive option because it exhibited the ability to suppress the formation of the dynamic stall vortex without either the added weight and complexities of mechanical systems or the complexity of the ducting involved with boundary-layer suction 9 . A disadvantage of the tangential wall blowing methods, proposed by McCloud et al 6 and Weaver et al 7 , was that they required a relatively high amount of blowing (C µ > 0.02) to be effective.…”

Ultra High Work, High Efficiency Turbines For UAVs

“…Weaver et al 27 found a 12% lift increase from steady suction / surface blowing and a 20% increase from pulsed blowing with an F+ of 0.9 and Cμ's of 0.19 to 0.56. Another separation control technique which has been successful is the "synthetic jet" 30,45,46 .…”

“…In addition to reducing the losses the loading can now also be significantly increased. ; blown flaps 26,27 ; suction or blowing 28 ; thermal riblets, 29 ; synthetic jets 6,[30][31][32][33] ; surface deformation 33 ; electrostatic and plasma interactions with flows [34][35][36][37][38] ; rapid transverse strain 39,40 ; acoustic cavities or acoustic forcing; electromagnetic flow interactions; and MEMS devices employing various combinations of the previous techniques.…”

Investigation of the benefits of unsteady blowing actuation on a 2D wind turbine blade

“…Leading-edge blowing on the suction side of the airfoil provides extra momentum into its boundary layer so that the flow could overcome a higher adverse pressure gradient, and hence be kept attached for higher angles of attack. Moreover, it has been shown Downloaded by [University of Alabama at Tuscaloosa] at 18:50 29 March 2015 [5][6][7] that oscillatory blowing at the leading edge can delay boundary-layer separation more effectively than steady blowing. This is because the large coherent structures introduced by oscillatory blowing enhance the transport of momentum across the shear layer, hence energizing the boundary layer in a more effective way.…”